1. Field of Invention
The present invention relates generally to vehicle headlamps and, more particularly, to a vehicle headlamp unit having an electrical connection that is compatible with both halogen and high intensity discharge (HID) lamps.
2. Related Technology
Different vehicle headlamp systems use different types of lamps. While they are most commonly equipped with halogen lamps, recently there has been a trend towards adopting high intensity discharge (HID) lamps. In a halogen lamp an electric current passes through a high-resistance tungsten filament which generates light. In an HID lamp, instead of a filament, an arc is created between a pair of electrodes, which excites a gas (commonly xenon) inside the lamp that vaporizes metallic salts. These metallic salts help sustain the arc and provide a consistent lamp intensity. Compared to HID lamps, halogen lamps operate at a low power voltage (12 or 24 volts) and can directly use the voltage from the vehicle power. HID lamps operate at much higher voltage, approximately 20 kilovolts (kV). Thus, a separate lighting circuit is required to generate the high voltage for lighting the HID lamp.
HID headlamp systems are attractive to automotive manufacturers because of their longer lifespan, better durability, and greater performance and power efficiency. Despite the numerous advantages of HID lamps, manufacturers have not entirely replaced halogen lamps with HID lamps because they are expensive compared, to halogen lamps. and they have a tendency to cause more discomfort glare for oncoming drivers. Accordingly, a vehicle may be designed to alternately accommodate halogen and HID headlamps, depending on which is desired by the end consumer. A unique wiring harness, for supplying power from the vehicle to the lamp, is currently required for each version of the headlamp due to the difference in design and power supply requirements in halogen and HID headlamps. This further increases cost and complexity in the internal structure of the vehicle by requiring different wire harness designs and components for each version.